1
4
2
What are the relative masses of a proton, neutron
and electron, given that a proton has a mass of 1?
How many protons, neutrons and electrons are
there in an atom of phosphorus, which has a proton
number of 15 and a mass number of 31?
3
Explain the terms atom and element, and include
a clear description of the relationship between the
two terms.
Explain why neutrons are important in making the
nucleus of an atom stable. You need to consider the
charges on the different subatomic particles present.